Weather Alert

Weather advisory

Date: 18 March 2018

Area’s affected:

KZN

Eastern Cape

Western Cape

Limpopo

Mpumalanga

Gauteng

Free State

North West Province

Northern Cape

Period: 18 March until 22 March 2018

For today (Monday), the risk of thunderstorms becomes far more likely over the highveld with isolated to scattered thunderstorms expected anywhere NE of a line Kuruman to Colesberg. Isolated to scattered thunderstorms are also likely today over the NE interior of the Eastern Cape with scattered thunderstorms likely over central and western parts of KZN and S parts of Mpumulanga - there is a small chance that these may become energetic in places. Elsewhere today, fine conditions are expected, although it will be cloudy along the Cape S coast with hot conditions expected along the lowveld and N parts of the Northern Cape.

By Tuesday afternoon, the dry line (area dividing dry air with no thunderstorm risk and moist air with thunderstorm risk) moves further NE on the highveld, therefore isolated to scattered thunderstorms are only expected NE of a line Mahikeng to Bethlehem but will also become far more likely over southern and western parts of Limpopo. Scattered thunderstorms are likely to continue over S parts of Mpumulanga and N parts of KZN but will become less likely (although isolated thunderstorms are still possible) over S parts of KZN and over the NE interior of the Eastern Cape. Elsewhere on Tuesday, conditions remain largely similar to Monday although most parts of the central interior will become hot and fresh NE winds may develop along the KZN coast.

On Wednesday and Thursday, thunderstorms should mostly clear the highveld as cold fronts begin to affect the Cape S coast. The first front, expected early in the morning on Wednesday, should clear the humidity over the area and also introduce a small chance of some light rain along the Garden Route and Eastern Cape Coast. The second front, expected early in the morning on Thursday, will be stronger with isolated but heavier showers expected along coastal areas along with fresh to strong W to SW winds. By Thursday afternoon, the front is expected to push into KZN with cooler conditions and showers over coastal areas and scattered thunderstorms over western and northern areas as well as southern parts of Mpumulanga - some of these thunderstorms are likely to be energetic in places as the cold front collides (converges) with warmer and more humid sub-tropical air.

Late on Thursday and into Friday morning, the thunderstorms are also likely to push onto eastern parts of the highveld with scattered (and potentially energetic) thunderstorms quite likely over the highveld on Friday afternoon and evening NE of a line Mahikeng to Maseru.

Over the weekend, most coastal areas should be dry although there is the chance of quite strong E to NE winds anywhere from Cape Agulhus to Richards Bay. Over the highveld, isolated to scattered afternoon thunderstorms are likely to continue although they are expected to be less widespread than on Friday. Temperatures are expected to rise over many parts of the country with potentially hot conditions in places, gusty and hot W winds are also likely over the central interior at times.

Storms containing large hail: (any mention of thunderstorms in the forecast automatically presumes a very low chance of hailstorms). Low chance today (Monday) over the NE interior of the Eastern Cape, S parts of Mpumulanga and central and W parts of KZN. Low chance on Tuesday over S parts of Mpumulanga and N parts of KZN.

Medium chance on Thursday over W and N parts of KZN and S parts of Mpumulanga. Medium chance on Friday over the highveld NE of a line Mahikeng to Maseru.

Medium chance today (Monday) over the NE interior of the Eastern Cape, S parts of Mpumulanga and central and W parts of KZN along with areas on the highveld NE of a line Kuruman to Colesberg. Medium chance on Tuesday over S parts of Mpumulanga and N parts of KZN along with areas on the highveld NE of a line Mahikeng to Bethlehem.

High chance on Thursday over W and N parts of KZN and S parts of Mpumulanga. High chance on Friday over the highveld NE of a line Mahikeng to Maseru with a medium chance over the weekend.

Flash flooding: (any mention of thunderstorms in the forecast automatically presumes a very low chance of flash flooding). Low to medium chance today (Monday) over the NE interior of the Eastern Cape, S parts of Mpumulanga and central and W parts of KZN with a low chance on the highveld NE of a line Kuruman to Colesberg.

Medium chance on Tuesday over S parts of Mpumulanga and N parts of KZN with a low chance on the highveld NE of a line Mahikeng to Bethlehem. Medium chance on Thursday over W and N parts of KZN and S parts of Mpumulanga. High chance on Friday over the highveld NE of a line Mahikeng to Maseru with a low chance over the weekend.

Fire risk: Chance of high fire dangers along the coast and adjacent interior over the weekend.

Other: Medium to high chance of strong winds along the Cape S coast on Thursday. High chance of strong winds in places along the coast between Richards Bay and Cape Agulhas over the weekend.